Energy converter, speaker, and method of manufacturing energy converter

ABSTRACT

An energy converter includes a permanent magnet and a diaphragm. The permanent magnet is fixed to a predetermined area. The diaphragm is disposed on the permanent magnet and has a coil formed of a conductor pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35U.S.C. §119(a) to Japanese Patent Application No. 2013-189112, filed onSep. 12, 2013, in the Japan Patent Office, Japanese Patent ApplicationNo. 2014-016415, filed on Jan. 31, 2014, in the Japan Patent Office,Japanese Patent Application No. 2014-079143, filed on Apr. 8, 2014, inthe Japan Patent Office, the entire disclosures of which are herebyincorporated by reference herein.

BACKGROUND

1. Technical Field

This disclosure relates to an energy converter and a speaker thatinterconvert electrical and mechanical energy, and a method ofmanufacturing the energy converter.

2. Related Art

Energy converters that interconvert electrical and mechanical energyinclude speakers and microphones. In a speaker, a coil adjacent to apermanent magnet is vibrated by repulsive force due to electromagneticinduction, causing a diaphragm fixed to the coil to vibrate the air andgenerate acoustic waves. In a microphone, acoustic waves vibrate adiaphragm, causing a current to flow through a coil connected with thediaphragm owing to electromagnetic induction.

In the past, speakers equipped with a conical diaphragm have beendominant. In recent years, however, thin speakers (so-called flatspeakers) equipped with a flat planar diaphragm have been drawingattention.

SUMMARY

In one embodiment of this disclosure, there is provided an improvedenergy converter that, in one example, includes a permanent magnet and adiaphragm. The permanent magnet is fixed to a predetermined area. Thediaphragm is disposed on the permanent magnet and has a coil formed of aconductor pattern.

In one embodiment of this disclosure, there is provided an improvedspeaker that, in one example, includes the above-described permanentmagnet and the above-described diaphragm.

In one embodiment of this disclosure, there is provided an improvedmethod of manufacturing an energy converter that, in one example,includes fixing a permanent magnet to a predetermined area, anddisposing on the permanent magnet a diaphragm having a coil formed of aconductor pattern. The disposing includes placing a magnetic sheetencapsulated with a magnetic fluid on the diaphragm to visualize amagnetization pattern of the permanent magnet disposed under thediaphragm as a shading pattern of the magnetic fluid, and adjusting thediaphragm in position and disposing the diaphragm at a position at whichthe shading pattern matches the conductor pattern of the coil.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of this disclosure and many of theadvantages thereof are obtained as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings, wherein:

FIGS. 1A and 1B are diagrams illustrating types of structures to which aspeaker according to an embodiment of this disclosure is attachable;

FIG. 2 is a diagram illustrating a diaphragm and a permanent magnetaccording to the embodiment;

FIGS. 3A to 3C are schematic diagrams illustrating a procedure tomanufacture the speaker according to the embodiment;

FIGS. 4A and 4B are a sectional view of the speaker according to theembodiment and an enlarged partial view thereof;

FIGS. 5A and 5B are enlarged partial sectional views of otherembodiments of the speaker according to the embodiment;

FIGS. 6A and 6B are diagrams illustrating a diaphragm according toanother embodiment of this disclosure;

FIGS. 7A and 7B are a sectional view of a speaker according to theembodiment in FIGS. 6A and 6B and an enlarged partial view thereof;

FIG. 8 is a diagram illustrating disposition of spacers according toanother embodiment of this disclosure;

FIGS. 9A and 9B are a sectional view of a speaker according to theembodiment in FIG. 8 and an enlarged partial view thereof;

FIGS. 10A and 10B are diagrams illustrating a diaphragm according toanother embodiment of this disclosure;

FIGS. 11A and 11B are diagrams illustrating a speaker according to theembodiment in FIGS. 10A and 10B;

FIGS. 12A and 12B are sectional views of the speaker according to theembodiment in FIGS. 11A and 11B;

FIGS. 13A to 13E are diagrams illustrating a process of manufacturing aspeaker according to another embodiment of this disclosure;

FIGS. 14A to 14D are conceptual diagrams illustrating a method ofpositioning a diaphragm according to the embodiment in FIGS. 13A to 13E;

FIG. 15 is a sectional view of the speaker according to the embodimentin FIG. 13E;

FIGS. 16A and 16B are diagrams illustrating a front surface and a rearsurface of the speaker according to the embodiment in FIG. 15,respectively;

FIGS. 17A and 17B are diagrams illustrating conditions of an experimentfor evaluating directivity characteristics;

FIGS. 18A to 18C are diagrams illustrating structures forming speakersaccording to embodiment examples of this disclosure;

FIGS. 19A and 19B are sectional views of a speaker according to anembodiment example of this disclosure;

FIGS. 20A and 20B are diagrams illustrating conditions of an experimentfor evaluating directivity characteristics;

FIGS. 21A to 21D are diagrams illustrating experimental results of anembodiment example of this disclosure;

FIGS. 22A to 22D are diagrams illustrating experimental results of anembodiment example of this disclosure;

FIGS. 23A to 23D are diagrams illustrating experimental results of anembodiment example of this disclosure;

FIGS. 24A to 24D are diagrams illustrating experimental results of anembodiment example of this disclosure;

FIGS. 25A to 25D are diagrams illustrating experimental results of anembodiment example of this disclosure;

FIGS. 26A to 26D are diagrams illustrating experimental results of anembodiment example of this disclosure;

FIGS. 27A to 27C are diagrams illustrating structures and a diaphragmforming speakers according to embodiment examples of this disclosure;

FIGS. 28A to 28D are diagrams illustrating experimental results ofembodiment examples of this disclosure; and

FIGS. 29A to 29D are diagrams illustrating experimental results ofreference examples.

DETAILED DESCRIPTION

In describing the embodiments illustrated in the drawings, specificterminology is adopted for the purpose of clarity. However, thisdisclosure is not intended to be limited to the specific terminology soused, and it is to be understood that substitutions for each specificelement can include any technical equivalents that have the samefunction, operate in a similar manner, and achieve a similar result.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views to omitredundant description thereof, and structures are illustrated ondifferent scales where necessary for the purpose of clarity, an energyconverter according to an embodiment of this disclosure will bedescribed with reference to embodiments of a speaker. This disclosure,however, is not limited to the following embodiments, and is alsoapplicable to other energy converters, such as microphones and fans.

A speaker according to an embodiment of this disclosure is additionallyattachable to a curved surface of a desired structure. FIGS. 1A and 1Billustrate types of areas to which the speaker according to the presentembodiment is attachable, i.e., a cylindrical area 50 (hereinafterreferred to as the cylinder 50) illustrated in FIG. 1A and a sphericalarea 52 (hereinafter referred to as the sphere 52) illustrated in FIG.1B.

Description will now be given of a procedure to additionally attach thespeaker to the cylinder 50.

In the present embodiment, a diaphragm 10 and a permanent magnet 20illustrated in FIG. 2 are first prepared.

The diaphragm 10 may be formed of a flexible resin substrate 12 having athickness of approximately 10 μm to approximately 30 μm. Preferably, theresin substrate 12 has a bending elastic modulus of approximately 2000MPa to approximately 3000 MPa, and may be made of polyethyleneterephthalate (PET), polyimide, or polyethylene naphthalate (PEN), forexample.

The resin substrate 12 has a horizontally long rectangular shape in FIG.2. It is preferable to set the resin substrate 12 to an appropriatewidth shorter than the length of the cylinder 50 and an appropriatelength substantially equal to the length of the outer circumference ofthe cylinder 50.

The resin substrate 12 has a surface formed with a coil 14 of ameandering or pulse-shaped conductor pattern, in which conductorsegments extending in the width direction of the resin substrate 12 areformed at a uniform pitch P. In the present embodiment, the conductorpattern may be formed by, for example, wet-etching the resin substrate12 foiled with copper or screen-printing on the resin substrate 12 witha copper paste. The coil 14 has a positive terminal 14 a and a negativeterminal 14 b to be connected to a power supply.

The permanent magnet 20 has a horizontally long rectangular shape inFIG. 2. The permanent magnet 20 is set to appropriate width and lengthin accordance with the width and length of the conductor pattern of thecoil 14. Preferably, the permanent magnet 20 is a bonded magnet (i.e.,rubber magnet) sheet readily deformable to fit the curved surface of thecylinder 50.

As illustrated in FIG. 2, the permanent magnet 20 has a magnetizationpattern of parallel stripes formed such that north (N)-pole bands andsouth (S)-pole bands extending in the width direction of the permanentmagnet 20 alternate. The magnetization pattern is configured to have thepitch P of the coil 14 formed on the diaphragm 10.

The permanent magnet 20 may be a ferrite magnet, a neodymium magnet, analnico magnet, a samarium cobalt magnet, or the like, preferably aneodymium magnet having high magnetic force.

After the preparation of the diaphragm 10 and the permanent magnet 20described above, the permanent magnet 20 is wrapped and fixed around theouter circumferential surface of the cylinder 50, as illustrated in FIG.3A. In the present embodiment, the permanent magnet 20 may be embeddedin the permanent magnet 20, specifically in a recess formed in the outercircumferential surface of the cylinder 50 having a depth equivalent tothe thickness of the permanent magnet 20.

Thereafter, a buffer film 30 is disposed to cover the entirety of asurface of the permanent magnet 20, as illustrated in FIG. 3B. Thebuffer film 30 thus disposed prevents adhesion between the diaphragm 10and the permanent magnet 20 and divided vibration of the diaphragm 10,and secures a range of motion allowing the diaphragm 10 to vibrate witha sufficient amplitude.

The buffer film 30 is made of a flexible non-magnetic material, and isinterposed between the permanent magnet 20 and the diaphragm 10 to keepthe permanent magnet 20 and the diaphragm 10 separated from each otherby a constant distance. In the present embodiment, the buffer film 30preferably has a thickness of a few micrometers to a few hundredmicrometers, and may be made of cellulose fiber, such as traditionalJapanese paper, cleaning paper, or cleaning wipes, for example, or anelastic material such as rubber.

Finally, the diaphragm 10 is curled (i.e., bent) in the longitudinaldirection thereof and disposed on the buffer film 30 to cover thepermanent magnet 20, and opposed ends of the diaphragm 10 are fixed onthe outer circumferential surface of the cylinder 50 with an appropriatefixing member 15, as illustrated in FIG. 3C.

In this process, it is desirable to position and fix the diaphragm 10 onthe outer circumferential surface of the cylinder 50 such that thesegments of the conductor pattern of the coil 14 on the diaphragm 10extending in the width direction match the boundaries between the N-polebands and the S-pole bands in the magnetization pattern of the permanentmagnet 20 disposed under the diaphragm 10.

FIG. 4A is a sectional view of a speaker 100 in FIG. 3C completedthrough the above-described procedure, along line IVA-IVA. FIG. 4B is anenlarged view of a portion of the sectional view enclosed by a brokenline.

In the enlarged view of FIG. 4B, magnetic lines of force arching fromthe N-pole to the S-pole on a surface of the permanent magnet 20 serveas magnetic field components. In particular, magnetic field componentsparallel to the surface of the permanent magnet 20 contributesubstantially to electromagnetic induction of the coil 14 formed on thediaphragm 10, and are maximized near the boundaries between the N-polebands and the S-pole bands of the magnetization pattern, i.e., theboundaries between the N-pole and the S-pole.

In the present embodiment, if a magnetic field is generated by analternating current supplied to the coil 14, repulsive force isgenerated in the coil 14 by electromagnetic induction in accordance withFleming's left-hand rule, vibrating the diaphragm 10 in the normaldirection of the outer circumferential surface of the cylinder 50. Ifthe diaphragm 10 is positioned such that the segments of the conductorpattern of the coil 14 extending in the width direction match theboundaries between the N-pole and the S-pole, as described above, thediaphragm 10 vibrates at the maximum efficiency, generating sufficientsound pressure for speaker use.

The magnetization pattern of the permanent magnet 20 and the conductorpattern forming the coil 14 are not limited to the above-describedembodiments, and may be any embodiment allowing the generation ofrepulsive force due to electromagnetic induction when a current issupplied to the coil 14.

FIGS. 5A and 5B illustrate other embodiments of the speaker 100. FIG. 5Aillustrates an embodiment in which the conductor pattern of the coil 14is formed on both surfaces of the resin substrate 12 in the diaphragm10. This embodiment increases the magnetic field to be generated by thesupplied current, thereby increasing the amplitude and generatinggreater sound pressure.

FIG. 5B illustrates an embodiment in which a high magnetic permeabilitysheet 40 made of a high magnetic permeability material is disposedbetween the permanent magnet 20 and the cylinder 50. According to thepresent embodiment, the high magnetic permeability sheet 40 reduces aleakage magnetic field on the rear side of the permanent magnet 20 andincreases a leakage magnetic field on the side of the diaphragm 10(i.e., on the side of the coil 14), thereby increasing the amplitude andgenerating greater sound pressure.

Following the above description of the speaker 100 according to anembodiment of this disclosure, a description will be given of a speaker200 according to another embodiment of this disclosure including amember replacing the above-described buffer film 30.

As illustrated in FIGS. 6A and 6B, in the speaker 200 according to thepresent embodiment, minute projections 16 made of an insulating materialare formed in dots on a surface of the diaphragm 10 facing the permanentmagnet 20. In the present embodiment, the projections 16 may be formedby, for example, ejecting a curable resin paste dispersed with finesilica particles onto the surface of the diaphragm 10 through nozzles orscreen-printing on the surface of the diaphragm 10 with the paste.

FIG. 7A is a sectional view of the speaker 200 including the diaphragm10 having the surface formed with the dot-shaped projections 16. FIG. 7Bis an enlarged view of a portion of the sectional view enclosed by abroken line.

As illustrated in the enlarged view of FIG. 7B, the speaker 200 does nothave the buffer film 30 disposed between the diaphragm 10 and thepermanent magnet 20. In the present embodiment, the buffer film 30 isreplaced by the projections 16 formed in dots on the surface of thediaphragm 10 facing the permanent magnet 20. The projections 16 preventadhesion between the diaphragm 10 and the permanent magnet 20 anddivided vibration of the diaphragm 10, and guarantee appropriatevibration of the diaphragm 10.

Following the above description of the speaker 200 according to anembodiment of this disclosure, a description will be given of a speaker300 according to another embodiment of this disclosure configured tosecure a greater range of motion of the diaphragm 10 than in theabove-described speaker 200.

As illustrated in FIG. 8, the speaker 300 according to the presentembodiment includes three linear spacers 22 formed on a surface of thepermanent magnet 20 to extend in the width direction of the permanentmagnet 20. In the present embodiment, the spacers 22 may be elasticmembers made of a non-magnetic material.

FIG. 9A is a sectional view of the speaker 300 having the spacers 22formed on the surface of the permanent magnet 20. FIG. 9B is an enlargedview of a portion of the sectional view enclosed by a broken line.

As illustrated in the enlarged view of FIG. 9B, the speaker 300 has thespacers 22 formed between the diaphragm 10 and the permanent magnet 20to increase the range of motion of the diaphragm 10, thereby increasingthe amplitude and generating greater sound pressure.

FIG. 8 illustrates an embodiment in which the spacers 22 are formed on asurface of the permanent magnet 20 to extend along the width directionof the permanent magnet 20 (i.e., the longitudinal direction of thecylinder 50). The positions of the spacers 22, however, are not limitedto those in the example illustrated in FIG. 8. As another embodiment,spacers may be formed on a surface of the permanent magnet 20 along thelongitudinal direction of the permanent magnet 20 (i.e., thecircumferential direction of the cylinder 50). Further, spacers may beformed as linear projections projecting from the outer circumferentialsurface of the cylinder 50 and extending along opposed edges of thepermanent magnet 20 (i.e., along the circumferential direction of thecylinder 50).

Following the above description of the speakers attachable to thecylinder 50, a procedure to additionally attach a speaker to the sphere52 illustrated in FIG. 1B will now be described.

FIGS. 10A and 10B illustrate a diaphragm 60 employed in this embodiment.As illustrated in FIG. 10A, the diaphragm 60 has the shape of sixspindle-shaped resin substrates 62 horizontally arranged and connectedas in a view of a spread-out sphere.

Each of the spindle-shaped resin substrates 62 has a conductor patternformed to extend along meridians of the sphere 52. The conductorpatterns formed on the resin substrates 62 are connected together atrespective positions at which the resin substrates 62 are connectedtogether, thereby forming a coil 64 having a positive terminal 64 a anda negative terminal 64 b. The resin substrates 62 may be made of amaterial similar to the material forming the resin substrate 12 in theforegoing embodiments. Similarly, the coil 64 may be made of a materialsimilar to the material forming the coil 14 in the foregoingembodiments.

In the present embodiment, the minute projections 16 made of aninsulating material are formed in dots on a surface of the diaphragm 60facing a later-described permanent magnet 70 by a method similar to themethod described with reference to FIGS. 6A and 6B. FIG. 10B illustratesthe diaphragm 60 having the surface formed with the dot-shapedprojections 16.

In the present embodiment, the permanent magnet 70 being a bonded magnetis fixed to the sphere 52 along the curved surface of the sphere 52 tosurround the outer circumference of the sphere 52, as illustrated inFIG. 11A.

As illustrated in FIG. 11A, the permanent magnet 70 has a magnetizationpattern of parallel stripes formed such that N-pole bands and S-polebands extending along the longitudinal direction of the sphere 52alternate. The magnetization pattern is configured to have the pitch Pof the coil 64 formed on the diaphragm 60.

Then, as illustrated in FIG. 11B, the diaphragm 60 is wrapped around thesphere 52 to cover the sphere 52 such that the surface of the diaphragm60 formed with the projections 16 faces inside. Thereafter, the verticesof the six resin substrates 62 are joined and fixed to the surface ofthe sphere 52 with appropriate fixing members 65.

In this process, it is desirable to position and fix the diaphragm 60 onthe surface of the sphere 52 such that the segments of the conductorpattern of the coil 64 on the diaphragm 60 extending in the longitudinaldirection of the sphere 52 match the boundaries between the N-pole andthe S-pole in the magnetization pattern of the permanent magnet 70located under the diaphragm 60.

FIG. 12A is a sectional view of a speaker 400 in FIG. 11B completedthrough the above-described procedure, along line XIIA-XIIA, and anenlarged view of a portion of the sectional view. FIG. 12B is asectional view of the speaker 400 along line XIIB-XIIB.

In the present embodiment, if a magnetic field is generated by analternating current supplied to the coil 64, repulsive force isgenerated in the coil 64 owing to electromagnetic induction inaccordance with Fleming's left-hand rule, vibrating the diaphragm 60 inthe normal direction of the surface of the sphere 52. If the diaphragm60 is positioned such that the conductor pattern of the coil 64 matchesthe boundaries between the N-pole and the S-pole, as described above,the diaphragm 60 vibrates at the maximum efficiency, generatingsufficient sound pressure for speaker use.

The magnetization pattern of the permanent magnet 70 and the conductorpattern forming the coil 64 are not limited to the above-describedembodiments, and may be any embodiment allowing the generation ofrepulsive force due to electromagnetic induction when a current issupplied to the coil 64.

As described above, according to an embodiment of this disclosure, it ispossible to additionally attach a speaker to a curved surface of adesired structure. As an application of this disclosure, it isconceivable to apply a speaker according to an embodiment of thisdisclosure to a curved surface of an existing structure.

A socket of a linear fluorescent lamp is an example of the existingstructure. When a typical conical speaker is additionally attached tosuch a socket, the speaker (or the diaphragm included therein) needs tobe small in size owing to the limitation of space. In that case,sufficient spread of sound is not expected.

In this regard, a speaker according to an embodiment of this disclosureis attachable to a cylindrical curved surface of the socket of thelinear fluorescent lamp. In this case, acoustic waves generated by thediaphragm having an arc curved surface propagate in a wide range in thenormal direction of the curved surface of the diaphragm.

The above-described embodiment using the socket of the linearfluorescent lamp is a mere example. Thus, any structure having a curvedsurface is usable as the area to which a speaker according to anembodiment of this disclosure is attached.

Further, although the speaker is additionally attached to a curvedsurface area of an existing structure in the above-described embodiment,a special structure for the speaker may, of course, be prepared.

Further, although the speaker is additionally attached to a curvedsurface of a structure in the foregoing description, a speaker accordingto another embodiment of this disclosure is additionally attached topyramidal surfaces of a structure having a pyramidal shape (including atruncated pyramidal shape) as the attachment area, realizingnon-directivity.

Further, although the speaker is constantly attached to a structurepreviously assumed as the attachment area in the foregoing description,a speaker according to another embodiment of this disclosure is freelyattachable to and detachable from a desired structure, not limited topreviously assumed structures. The speaker according to the embodimentattachable to and detachable from a desired structure will now bedescribed.

With reference to FIGS. 13A to 13E, a process of manufacturing a speaker500 according to this embodiment will be described.

In the present embodiment, a band-shaped plastic substrate 80 is firstprepared, and the permanent magnet 20 is disposed at the center of theplastic substrate 80, as illustrated in FIG. 13A. The plastic substrate80 is made of a plastic material. Preferably, the plastic substrate 80is heat-conductive in consideration of the possibility of being attachedto a heat source such as a fluorescent lamp. Further, preferably, theplastic substrate 80 is flame-retardant from a safety perspective, andhas electromagnetic shielding performance sufficient to attain a highsignal-to-noise (S/N) ratio.

Then, as illustrated in FIG. 13B, an adhesive agent 82 is applied to anarea in the plastic substrate 80 not having the permanent magnet 20 andthe side surfaces of the permanent magnet 20. In this process, theadhesive agent 82 is not applied to the upper surface of the permanentmagnet 20. The adhesive agent 82 is neither applied to one end portionof the plastic substrate 80, to which a later-described hook-and-loopfastener 85 is to be attached later. In the present embodiment, theadhesive agent 82 may be replaced by a double-sided adhesive tape.

As illustrated in FIG. 13C, the buffer film 30 is then disposed on thepermanent magnet 20. As described above with reference to FIG. 3B, thebuffer film 30 made of a flexible non-magnetic material is interposedbetween the permanent magnet 20 and the diaphragm 10 to keep thepermanent magnet 20 and the diaphragm 10 separated from each other by aconstant distance. The buffer film 30 may be made of cellulose fiber,such as traditional Japanese paper, cleaning paper, or cleaning wipes,or an elastic material such as rubber.

Then, as illustrated in FIG. 13D, the diaphragm 10 is disposed on thebuffer film 30. In this process, it is desirable to position and disposethe diaphragm 10 such that the segments of the conductor pattern of thecoil 14 on the diaphragm 10 extending in the width direction of the coil14 match the boundaries between the N-pole and the S-pole in themagnetization pattern of the permanent magnet 20 located under thediaphragm 10.

FIG. 14A to 14D are conceptual diagrams illustrating a method ofpositioning the diaphragm 10. According to this method, in the processof disposing the diaphragm 10 on a laminate of the permanent magnet 20and the buffer film 30, a magnetic sheet 90 is placed on the diaphragm10 to partially expose the conductor pattern of the coil 14, asillustrated in FIG. 14A. The magnetic sheet 90 is a film sheet having amagnetic fluid uniformly distributed and encapsulated therein, servingas a functional sheet capable of visualizing the magnetization patternof a magnet.

In the magnetic sheet 90 placed on the diaphragm 10, the magnetizationpattern of the permanent magnet 20 disposed under the buffer film 30 isvisualized as a shading pattern of the magnetic fluid, as illustrated inFIG. 14B. With this mechanism, the diaphragm 10 is adjusted in positionto be disposed at a position at which the shading pattern appearing onthe magnetic sheet 90 matches the conductor pattern of the coil 14, asillustrated in FIG. 14C. Consequently, the diaphragm 10 is disposed suchthat the positions of the segments of the conductor pattern of the coil14 extending in the width direction match the boundaries between theN-pole and the S-pole in the magnetization pattern of the permanentmagnet 20 disposed under the coil 14, as illustrated in a cut-outportion of the diaphragm 10 in FIG. 14D. The above-described positioningmethod is, of course, similarly applicable to other embodiments of thisdisclosure.

Finally, a protective sheet 84 having the same width as the width of theplastic substrate 80 is disposed on the diaphragm 10, and outer edgeportions of the protective sheet 84 are bonded to the plastic substrate80 with the adhesive agent 82, as illustrated in FIG. 13E. Thereby, theband-shaped speaker 500 is obtained. Preferably, the protective sheet 84is made of a material that transmits sound, such as a porous material,and is water-repellant and flame-retardant.

FIG. 15 is a sectional view along line XV-XV in FIG. 13E. In FIG. 15,the scale is increased in the thickness direction for the sake ofclarity. In the speaker 500, a laminate structure including thepermanent magnet 20, the buffer film 30, and the diaphragm 10 disposedon the plastic substrate 80 is fixed by the protective sheet 84 coveringand sealing the laminate structure, as illustrated in FIG. 15.

Further, in the present embodiment, opposed end portions of theband-shaped speaker 500 are provided with the hook-and-loop fastener 85,as illustrated in FIGS. 16A and 16B, allowing simple attachment anddetachment of the speaker 500. In the example illustrated in FIGS. 16Aand 16B, a male surface 86 of the hook-and-loop fastener 85 is providedto an end portion of the front surface of the speaker 500 in FIG. 13Enot applied with the adhesive agent 82, and a female surface 88 of thehook-and-loop fastener 85 is provided to an end portion of the rearsurface of the speaker 500 on the opposite side of the end portion ofthe speaker 500 having the male surface 86. In the example illustratedin FIGS. 16A and 16B, it is possible to easily attach the speaker 500 toa desired structure (e.g., a fluorescent lamp) by wrapping the speaker500 around the structure with the protective sheet 84 facing out andsticking the male surface 86 and the female surface 88 of thehook-and-loop fastener 85 together. Similarly, it is possible to easilydetach the speaker 500 from the structure by separating the male surface86 and the female surface 88 of the hook-and-loop fastener 85 from eachother.

This disclosure has been described above with reference to severalembodiments, but is not limited to the above-described embodiments. Forexample, it is preferable to perform surface treatment on theabove-described magnets to prevent the magnets from rusting, and coverthe outermost surfaces of the speakers with a protective sheet such as aporous fluorine film to protect the speakers. Although an energyconverter according to an embodiment of this disclosure has beendescribed above with reference to embodiments of a speaker, thisdisclosure is, of course, also applicable to a microphone. Further, theelements disclosed in the foregoing embodiments may be combined in otherembodiments not explicitly disclosed herein, and any other embodimentsconceivable by a person skilled in the art and having the functions andeffects of this disclosure are included in the scope of this disclosure.

An energy converter according to an embodiment of this disclosure willnow be described more specifically with reference to embodimentexamples. This disclosure, however, is not limited to the followingembodiment examples.

The speakers according to the above-described embodiments were produced,and an experiment was conducted to evaluate the directivity of thespeakers.

In the production of the speakers, five speakers attached to a curvedsurface of a polycarbonate cylinder as the attachment area were producedas embodiment examples E1 to E5, and a speaker attached to a curvedsurface of a polycarbonate sphere as the attachment area were producedas embodiment example E6.

In embodiment example E1, a 20 μm-thick polyimide resin film having onesurface formed with a coil of a copper pattern having a thickness of 9μm and a pitch of 3 mm was used as the diaphragm. In embodiment examplesE2 to E6, a 20 μm-thick polyimide resin film with the same coil formedin both surfaces as described above was used as the diaphragm.

In embodiment examples E1, E2, E3, E5, and E6, a bonded neodymium magnethaving a leakage magnetic field of ±100 gauss, a thickness of 1 mm, anda pitch of 3 mm was externally attached to the attachment area. Inembodiment example E4, the same magnet as described above was embeddedin the attachment area such that the magnet is flush with thesurrounding area.

In embodiment examples E3, E4, and E5, linear rubber members each havinga width of 2 mm, a length of 24 mm, and a thickness of 1 mm weredisposed as spacers, as illustrated in FIG. 8.

In embodiment example E5, a high magnetic permeability magnetic sheetBUSTERAID FK3 manufactured by NEC-TOKIN Corporation was disposed betweenthe bonded neodymium magnet and the attachment area.

In embodiment example E6, the 20 μm-thick polyimide resin film was cutin the shape of spindles, and a surface of the polyimide resin film toface the magnet was formed with dot-shaped projections. In the presentembodiment example, the dot-shaped projections were formed by applyingand hardening a paste of tetraethyl orthosilicate dispersed with silicacomposite particles having an average particle diameter of approximately5 μm and added with an ethyl cellulose binder by the use of a jetdispenser Aero Jet manufactured by Musashi Engineering, Inc. and havinga needle diameter of 0.3 mm.

In comparative example C1, a speaker was produced by externallyattaching a bonded neodymium magnet having a leakage magnetic field of±100 gauss and a thickness of 1 mm to a flat surface of a flatpolycarbonate plate as the attachment area, and disposing a diaphragm onthe magnet. The diaphragm employed here is a 20 μm-thick polyimide resinfilm having one surface formed with a coil of a copper pattern having athickness of 9 μm.

TABLE 1 given below summarizes conditions for producing the speakers inthe present experiment.

TABLE 1 shape of dot-shaped magnetic base magnet spacers projectionscoil sheet E1 cylinder externally absent absent one surface absentattached E2 cylinder externally absent absent both surfaces absentattached E3 cylinder externally present absent both surfaces absentattached E4 cylinder embedded present absent both surfaces absent E5cylinder externally present absent both surfaces present attached E6sphere externally absent present both surfaces absent attached C1 flatplate externally absent absent one surface absent attached

In the evaluation of directivity, the sound output from each of thespeakers produced in the above-described procedures was measured with anon-directional microphone Type 4152 manufactured by Aco Co., Ltd. toevaluate the directivity of the speaker. In the present experiment, thedistance between the speaker and the microphone was set to 50 cm. Thesound output from the speaker was measured at four measurement positionsillustrated in FIG. 17A indicated as relative angles 0°, 30°, 60°, and90° in the circumferential direction of the speaker to a reference linepassing through the center of the speaker and four measurement positionsillustrated in FIG. 17B indicated as relative angles 0°, 30°, 45°, and60° in the longitudinal direction of the speaker to the reference linepassing through the center of the speaker.

In the present measurement, two types of sounds, i.e., sound at 10 KHzand sound at 20 KHz, generated by free software WaveGene Ver 1.4 foroutputting sound at a single frequency were output from the speaker andmeasured with sound pressure measuring software Spectra developed by AcoCo., Ltd. TABLE 2 given below summarizes measurement results obtained atthe four positions illustrated in FIG. 17A. TABLE 3 given belowsummarizes measurement results obtained at the four positionsillustrated in FIG. 17B.

TABLE 2 rms sound pressure (dB) rms sound pressure (dB) at frequency of10 KHz at frequency of 20 KHz measurement position (angle) measurementposition (angle) 0 30 60 90 0 30 60 90 E1 81 81 81 66 60 62 62 59 E2 8686 86 68 65 68 68 65 E3 87 87 87 69 70 70 70 67 E4 88 88 88 70 71 71 7168 E5 89 89 89 69 72 72 72 69 E6 88 88 88 88 71 71 71 71 C1 81 78 67 3560 51 47 33

TABLE 3 rms sound pressure (dB) rms sound pressure (dB) at frequency of10 KHz at frequency of 20 KHz measurement position (angle) measurementposition (angle) 0 30 45 60 0 30 45 60 E1 81 81 78 71 60 62 54 51 E2 8686 83 75 65 67 60 55 E3 87 86 83 77 70 70 62 57 E4 88 88 84 78 71 71 6358 E5 89 88 85 78 72 71 63 58 E6 88 88 85 77 71 71 63 57 C1 81 78 62 3460 58 41 32

It has been found from the measurement results in TABLE 2 and TABLE 3given above that the measured sound pressure (dB) is reduced with theincrease of the relative angle to the reference line perpendicular tothe flat planar diaphragm in comparative example C1, indicatingdirectivity of the speaker, whereas there is no substantial change inthe measured sound pressure (dB) with the increase of the relative anglein embodiment examples E1 to E6.

Further, speakers each including a bobbin-shaped structure wereproduced, and an experiment was conducted to evaluate the directivity ofthe speakers.

In the production of the speakers, bobbin-shaped structures 600 a to 600c illustrated in FIGS. 18A to 18 c, respectively, were produced ofpolycarbonate. In the structure 600 a, paired fringes 602 are formedalong opposed edges of a cylindrical body of the structure 600 a, andpaired linear projections 604 are formed on the outer circumferentialsurface of the cylindrical body of the structure 600 a to extend aroundthe entire circumference of the cylindrical body at respective positionsinside the fringes 602. Further, a band-shaped projection 606 havingscrew holes 608 a is formed on the outer circumferential surface of thecylindrical body of the structure 600 a to be flush with the pairedlinear projections 604. In the structure 600 b, linear projections 604 beach having a length of 10 mm are formed at regular intervals. In thestructure 600 c, linear projections 604 c each having a length of 5 mmare formed at regular intervals.

In embodiment example E7, a speaker was produced by externally fixing abonded neodymium magnet having a leakage magnetic field of ±100 gauss, athickness of 1 mm, and a pitch of 3 mm to an area of the above-producedstructure 600 a between the paired linear projections 604, and disposinga diaphragm to cover the magnet. The diaphragm employed here is a 20μm-thick polyimide resin film with a coil of a copper pattern having athickness of 9 μm and a pitch of 3 mm formed in both surfaces.

FIG. 19A is a sectional view of the speaker produced in theabove-described procedure, along line XIXA-XIXA in FIG. 18A. FIG. 19B isa sectional view of the thus-produced speaker along line XIXB-XIXB inFIG. 18A.

As illustrated in FIG. 19A, in the present embodiment example, theopposed ends of the diaphragm 10 are superimposed upon each other on theband-shaped projection 606 having the screw holes 608 a, and fixed withscrews 608 b. Further, as illustrated in FIG. 19B, a gap of 0.5 mm ismaintained between the magnet 20 and the diaphragm 10 resting on andsupported by the paired linear projections 604 functioning as spacers.

In embodiment examples E8 and E9, speakers were produced with the sameprocedure as described above with the structures 600 b and 600 c,respectively.

In embodiment examples E10, E11, and E12, speakers were produced withthe same procedure as described above with the structures 600 a, 600 band 600 c, respectively, and a diaphragm having slits. The slits wereformed along the opposed edges of the diaphragm at respective positionscontacting with the linear projections 604, such as a position Sillustrated in FIG. 19B. In embodiment example E13, a speaker wasproduced by further providing a protective sheet on a diaphragm havingslits, superimposing the opposed ends of the protective sheet on eachother on the band-shaped projection 606, and fixing the opposed ends ofthe protective sheet with screws. The protective sheet employed here isa porous fluorine film, i.e., an sa-PTFE vent filter manufactured byNIPPON Valqiua Industries, Ltd.

TABLE 4 given below summarizes conditions for producing theabove-described speakers.

TABLE 4 slits protec- in dia- tive shape of base magnet phragm sheet E7bobbin with linear projections externally absent absent extending aroundentire attached circumference E8 bobbin with 10 mm-long linearexternally absent absent projections attached E9 bobbin with 5 mm-longlinear externally absent absent projections attached E10 bobbin withlinear projections externally present absent extending around entireattached circumference E11 bobbin with 10 mm-long linear externallypresent absent projections attached E12 bobbin with 5 mm-long linearexternally present absent projections attached E13 bobbin with linearprojections externally present present extending around entire attachedcircumference

In the evaluation of directivity, the sound output from each of thespeakers produced in the above-described procedures was measured toevaluate the directivity of the speaker. In the present experiment, thedistance between the speaker and the microphone was set to 1 m and 2 m,and four types of sounds, i.e., sound at 10 KHz, sound at 14 KHz, soundat 18 KHz, and sound at 20 KHz, were output from the speaker andmeasured with the sound pressure measuring software at four measurementpositions illustrated in FIG. 20A indicated as relative angles 0°, 30°,45°, and 60° in the circumferential direction of the speaker relative tothe reference line passing through the center of the speaker and fourmeasurement positions illustrated in FIG. 20B indicated as relativeangles 0°, 30°, 45°, and 60° in the longitudinal direction of thespeaker relative to the reference line passing through the center of thespeaker.

FIGS. 21A to 26D illustrate measurement results of embodiment examplesE7 to E12. Measurement results of embodiment example E13 have been foundto be substantially the same in value as the measurement results ofembodiment example E10 except for the sound pressure at 20 KHz beinglower than that of embodiment example E10 by 2 dB. Thus, illustration ofthe measurement results of embodiment example E13 is omitted here.

It has been found from the measurement results illustrated in FIGS. 21Ato 26D that there is no substantial change in the measured soundpressure (dB) with the increase of the relative angle in embodimentexamples E7 to E13.

Further, a speaker including a structure having a quadrangular pyramidshape and a speaker including a structure having a truncatedquadrangular pyramid shape were produced, and an experiment wasconducted to evaluate the directivity of the speakers.

In the production of the speakers, a structure 700 a having asubstantially quadrangular pyramid shape illustrated in FIG. 27A and astructure 700 b having a substantially truncated quadrangular pyramidshape illustrated in FIG. 27B were produced of anacrylonitrile-butadiene-styrene (ABS) resin. In each of the structures700 a and 700 b, linear projections 702 functioning as spacers areformed at positions corresponding to the ridge lines of the pyramid.

In embodiment example E14, a speaker was produced by embedding andfixing a bonded neodymium magnet having a leakage magnetic field of ±100gauss, a thickness of 1 mm, and a pitch of 3 mm in four triangularpyramidal surfaces of the above-produced structure 700 a, and disposinga diaphragm 710 illustrated in FIG. 27C to cover the magnet. Thediaphragm employed here is a 20 μm-thick polyimide resin film having acoil of a copper pattern having a thickness of 9 μm and a pitch of 3 mmformed in both surfaces. In embodiment example E15, a speaker wasproduced in a similar procedure as described above by externallyattaching and fixing the bonded neodymium magnet on four trapezoidalpyramidal surfaces of the above-produced structure 700 b, and disposingthe diaphragm 710 to cover the magnet.

TABLE 5 given below summarizes conditions for producing theabove-described speakers.

TABLE 5 slits protec- in dia- tive shape of base magnet phragm sheet E14quadrangular pyramid embedded absent absent E15 truncated quadrangularexternally absent absent pyramid attached

In the evaluation of directivity, the sound output from each of thespeakers produced in the above-described procedures was measured toevaluate the directivity of the speaker. In the present experiment, thedistance between the speaker and the microphone was set to 1 m and 2 in,and four types of sounds, i.e., sound at 10 KHz, sound at 14 KHz, soundat 18 KHz, and sound at 20 KHz, were output from the speaker andmeasured with the sound pressure measuring software at the fourmeasurement positions illustrated in FIG. 20A indicated as the relativeangles 0°, 30°, 45°, and 60° to the reference line passing through thecenter of the speaker.

FIGS. 28A and 28B illustrate measurement results of embodiment exampleE14. FIGS. 28C and 28D illustrate measurement results of embodimentexample E15. It has been found from the measurement results illustratedin FIGS. 28A to 28D that there is no substantial change in the measuredsound pressure (dB) with the increase of the relative angle inembodiment examples E14 and E15.

Further, a band-shaped speaker was produced in the procedure describedwith reference to FIGS. 13A to 13E, and an experiment was conducted toevaluate the directivity of the speaker.

In the production of the speaker, a flame-retardant sheet, specificallya flame-retardant conductor pattern film manufactured by Seiren Co.,Ltd., was prepared as a sheet member and cut in a rectangle having awidth of 40 mm, a length of 165 mm, and a thickness of 165 Then, abonded neodymium magnet having a leakage magnetic field of ±100 gauss, awidth of 25 mm, a length of 90 mm, a thickness of 1 mm, and a pitch of 3mm was disposed on the flame-retardant sheet and fixed thereto with adouble-sided adhesive tape made of a flame-retardant acrylic materialand manufactured by 3M Company to prevent the bonded neodymium magnetfrom moving. Then, a non-magnetic rubber sheet the same in size as thebonded neodymium magnet was placed on the bonded neodymium magnet.Thereafter, a polyimide resin film having a width of 25 mm, a length of110 mm, and a thickness of 20 μm with a coil of a copper pattern havinga thickness of 9 μm and a pitch of 3 mm formed in both surfaces wasprepared as the diaphragm and positioned on the rubber sheet by themethod described with reference to FIGS. 14A to 14D. Further, a sheethaving a water-repellent treated surface is disposed on the diaphragm tocover the diaphragm, and outer edges of the sheet having thewater-repellent surface were fixed to the flame-repellant sheet with adouble-sided adhesive tape. Finally, a 40 mm×25 mm piece ofhook-and-loop fastener New ECOMAGIC Heat Resistant Type manufactured byMorito Co., Ltd. was attached to the front and rear surfaces of alaminate of the magnet, the diaphragm, and the sheets described above inthe manner illustrated in FIGS. 16A and 16B, to thereby obtain aband-shaped speaker.

In the evaluation of the directivity of the speaker manufactured in theabove-described procedure, the sound output from the speaker with themale and female surfaces of the hook-and-loop fastener stuck to eachother was measured to examine the directivity of the speaker. In thisexperiment, the distance between the speaker and the microphone was setto 1 m and 2 m, and four types of sounds, i.e., sound at 10 KHz, soundat 14 KHz, sound at 18 KHz, and sound at 20 KHz, were output from thespeaker and measured with the sound pressure measuring software at thefour measurement positions illustrated in FIG. 20A indicated as therelative angles 0°, 30°, 45°, and 60° in the circumferential directionof the speaker to the reference line passing through the center of thespeaker and the four measurement positions illustrated in FIG. 20Bindicated as the relative angles 0°, 30°, 45°, and 60° in thelongitudinal direction of the speaker to the reference line passingthrough the center of the speaker. Measurement results obtained therebyare substantially the same in value as the measurement results ofembodiment example E10.

As reference examples, the directivity of a commercially available flatspeaker and the directivity of a commercially available normal conicalspeaker were also examined under the same conditions as described above.FIGS. 29A and 29B illustrate measurement results of the commerciallyavailable flat speaker. FIGS. 29C and 29D illustrate measurement resultsof the commercially available normal conical speaker. As illustrated inFIGS. 29A to 29D, the sound pressure of the sound output from each ofthe commercially available speakers is substantially different dependingon the relative angle.

It has been found from the above-described experimental results that thespeakers according to embodiments of this disclosure arenon-directional.

According to an embodiment of this disclosure, a novel energy converterattachable to a desired structure is provided. The energy converteraccording to an embodiment of this disclosure is applicable to speakersand microphones, for example.

The above-described embodiments are illustrative and do not limit thisdisclosure. Thus, numerous additional modifications and variations arepossible in light of the above teachings. For example, elements orfeatures of different illustrative and embodiments herein may becombined with or substituted for each other within the scope of thisdisclosure and the appended claims. Further, features of components ofthe embodiments, such as number, position, and shape, are not limited tothose of the disclosed embodiments and thus may be set as preferred.Further, the above-described steps are not limited to the orderdisclosed herein. It is therefore to be understood that, within thescope of the appended claims, the disclosure of this disclosure may bepracticed otherwise than as specifically described herein.

What is claimed is:
 1. An energy converter comprising: a permanentmagnet fixed to an area of the converter; and a diaphragm disposed onthe permanent magnet and having a coil formed of a conductor pattern;the permanent magnet including a deformable magnetic sheet; wherein thearea of the converter is a non-flat surface; and wherein the permanentmagnet is fixed around the non-flat surface.
 2. The energy converteraccording to claim 1, further comprising: spacers formed between thediaphragm and the permanent magnet to secure a range of motion of thediaphragm.
 3. The energy converter according to claim 1, wherein thediaphragm has a surface facing the permanent magnet and having minuteprojections formed in dots.
 4. The energy converter according to claim1, further comprising: a buffer film disposed between the diaphragm andthe permanent magnet to secure a range of motion of the diaphragm. 5.The energy converter according to claim 1, wherein the conductor patternis formed on both surfaces of the diaphragm.
 6. The energy converteraccording to claim 1, wherein the area of the converter is one of acylindrical curved surface and a spherical curved surface.
 7. The energyconverter according to claim 1, wherein the area of the converter ispyramidal surfaces of one of a pyramid and a truncated pyramid.
 8. Theenergy converter according to claim 1, wherein the permanent magnet is abonded magnet.
 9. The energy converter according to claim 1, wherein thediaphragm includes a resin substrate.
 10. The energy converter accordingto claim 1, further comprising: a plastic substrate on which thepermanent magnet is fixed; a buffer film disposed between the permanentmagnet and the diaphragm to secure a range of motion of the diaphragm;and a protective sheet covering the diaphragm and fixed to the plasticsubstrate.
 11. The energy converter according to claim 10, wherein theprotective sheet is water-repellant and sound-transmissive.
 12. Theenergy converter according to claim 10, wherein the plastic substrate isflame-retardant.
 13. The energy converter of claim 1, wherein the areaof the converter is a curved surface.
 14. A speaker comprising: apermanent magnet fixed to an area of the speaker; and a diaphragmdisposed on the permanent magnet and having a coil formed of a conductorpattern; the permanent magnet including a deformable magnetic sheet;wherein the area of the speaker is a non-flat surface; and wherein thepermanent magnet is fixed around the non-flat surface.
 15. The speakeraccording to claim 14, further comprising: a plastic substrate on whichthe permanent magnet is fixed; a buffer film disposed between thepermanent magnet and the diaphragm to secure a range of motion of thediaphragm; and a protective sheet covering the diaphragm and fixed tothe plastic substrate.
 16. The speaker of claim 14, wherein the area ofthe speaker is a curved surface.
 17. A method of manufacturing an energyconverter, the method comprising: fixing a permanent magnet to an areaof the converter; and disposing on the permanent magnet a diaphragmhaving a coil formed of a conductor pattern, including: placing amagnetic sheet encapsulated with a magnetic fluid on the diaphragm tovisualize a magnetization pattern of the permanent magnet disposed underthe diaphragm as a shading pattern of the magnetic fluid, and adjustingthe diaphragm in position and disposing the diaphragm at a position atwhich the shading pattern matches the conductor pattern of the coil;wherein the permanent magnet is fixed around the non-flat surface.